It has been well known that a silver halide color photosensitive material forms a dye image by an imagewise exposure of the photosensitive material to light and a color development of the material. The dyes in the obtained image, such as indophenol, indoaniline, indamine, azomethine, phenoxazine and phenazine dyes are formed by a reaction of an oxidized aromatic primary amine color developing agent with a coupler in the color development.
In general, the quality of the obtained photographic image is not perpetual, and is gradually degraded while the photograph is preserved. A color photograph having an image made of an azomethine or indoaniline dye is particularly apt to be degraded. The degradation of the image is caused by a fading or discoloration of the dye image or a discoloration on a white ground (yellow stain), when the photograph is irradiated with light for a long term, or preserved at a high temperature and humidity.
The degradation of the image quality is a serious disadvantage. An improvement is desirable to overcome the disadvantage.
A color photograph generally contains cyan, magenta and yellow dye images. The magenta dye image was particularly investigated to stabilize the photograph, since the magenta dye was less stable than the other dyes. The stability of the magenta dye image has recently been so much improved as the results of the investigation that a fading or discoloration of the yellow or cyan dye image now becomes remarkable.
In order to improve the stability of the yellow dye image and the cyan dye image to light, heat or humidity, various compounds to be used in a photosensitive material have been proposed. For example, 2,2,6,6-tetraalkylpiperidine derivatives, the other piperidine derivatives and phenol derivatives are disclosed in British Patents No. 1,326,889, No. 1,354,313, No. 1,410,846, U.S. Pat. Nos. 3,336,135 and 4,268,593, Japanese Patent Publications No. 48(1973)-31256, No. 51(1976)-1420, No. 52(1977)-6623; and Japanese Patent Provisional Publications No. 58(1983)-114036, No. 59(1984)-5426, No. 59(1984)-124340, No. 60(1985)-222853, No. 60(1985)-222854, No. 62(1987)-262047, No. 63(1988)-113536 and No. 63(1988)-208844.
The present inventors also have proposed various 2,2,6,6-tetraalkylpiperidine derivatives and phenol derivatives in Japanese Patent Provisional Publications No. 61(1986)-2151, No. 61(1986)-4045, No. 61(1986)-6652, No. 61(1986)-167953, No. 62(1987)-115157, No. 63(1988)-9866 and No. 63(1988)-85547.
In order to improve the stability of the dyes to light or heat, the compounds disclosed in the above-mentioned publications have an effect on the dyes to some extent. However, the effect is relatively weak or is accompanied by a bad effect on the quality of the photograph. For example, a change of hue, an occurrence of fog, a precipitation in a coating layer and a change of the gradation of the photosensitive material are observed. Particularly, 2,2,6,6-tetraalkylpiperidines proposed in the above-mentioned publications and tertiary amines are only slightly soluble in a high boiling organic solvent, and they thus tend to degrade the quality of the photograph (e.g., gradation, sensitivity and color formation of the photograph). Further, even if the compounds disclosed in the above-mentioned publications have an effect on the cyan or magenta dye images to improve the stability of the dyes to light or heat, many of the compounds tend to increase an occurrence of a yellow stain on a white ground within the exposed ares when the photograph is irradiated with light or preserved at a high temperature and humidity.
On the other hand, various color image stabilizers have been proposed to improve the stability of the magenta dye image. Most of the color image stabilizers do not have any effect on the yellow and cyan dye images, and have the effect only on the magenta dye image. Moreover, many of the color image stabilizers adversely accelerate the fading of the yellow and cyan dye images.